Prostate-specific antigen (PSA) decline with apalutamide therapy is associated with longer survival and improved outcomes in individuals with metastatic prostate cancer: a plain language summary of the TITAN study

WHAT IS THIS SUMMARY ABOUT?

This summary describes the results from an additional (or post hoc) analysis of the TITAN study. The TITAN study looked at whether the prostate cancer treatment apalutamide could be used to treat individuals with metastatic castration-sensitive prostate cancer (or mCSPC). A total of 1052 participants with mCSPC were included in the TITAN study. Treatment with apalutamide was compared with treatment with placebo. All participants received androgen deprivation therapy (or ADT), which is a type of hormone therapy that has been part of the main treatment for mCSPC for many years. The results showed that apalutamide plus ADT increased the length of time that participants remained alive compared with placebo plus ADT. Apalutamide plus ADT also controlled the growth of the cancer for a longer length of time compared with placebo plus ADT. Additionally, participants who received apalutamide plus ADT experienced a greater reduction in the blood levels of prostate-specific antigen (or PSA), called a deep PSA decline, compared with those who received placebo plus ADT. An additional (or post hoc) analysis was carried out to understand whether a decrease in blood PSA levels, in response to treatment, was associated with improved outcomes, including longer survival time.

WHAT WERE THE RESULTS OF THE ADDITIONAL ANALYSIS?

In participants who received apalutamide plus ADT, a deep PSA decline in response to treatment was associated with longer survival time and improved outcomes.

WHAT DO THESE RESULTS MEAN FOR INDIVIDUALS WITH MCSPC?

These results demonstrate that individuals with mCSPC can benefit from treatment with apalutamide plus ADT. The association seen between deep PSA decline and the longer survival time and improved outcomes highlights how PSA measurements can be used to help monitor cancer disease evolution in response to treatment. Monitoring PSA levels will assist doctors and other healthcare professionals to understand how effectively a treatment is working for a patient and to tailor their treatment approach to improve PSA decline.

Real-world prostate-specific antigen response and progression to castration-resistant prostate cancer among men with metastatic castration-sensitive prostate cancer treated with apalutamide: a multi-institutional study in the Chu-shikoku Japan Urological Consortium

BACKGROUND

Japanese men receiving apalutamide often experience skin-adverse events (AEs), possibly requiring treatment interruption or dose reduction. However, concerns have arisen regarding the impact of these adjustments on the efficacy of apalutamide. Our study evaluated the efficacy, safety, and persistence of apalutamide in men with metastatic castration-sensitive prostate cancer (mCSPC).

METHODS

We retrospectively reviewed the medical records of 108 men with mCSPC from 14 Japanese institutions. The primary outcomes were the efficacy of apalutamide: prostate-specific antigen (PSA) response (50%, 90% and < 0.2 decline) and progression to castration-resistant prostate cancer (CRPC). The secondary outcomes were the skin-AE and compliance of apalutamide.

RESULTS

PSA50%, PSA90% and PSA < 0.2 declines were observed in 89.8, 84.3 and 65.7%, and the median time to CRPC progression was not reached. PSA < 0.2 decline and an initial full dose of apalutamide were significantly associated with a longer time to CRPC. The most common AE was skin-AE (50.9%), and there was no association between the occurrence of skin-AE and the time to CRPC (P = 0.72). The median apalutamide persistence was 29 months, which was longer in the initial full dose recipients than in the reduced dose recipients. The dosage is reduced in about 60% of patients within the first year of treatment in the initial full dose recipients.

CONCLUSIONS

Our findings indicate the effectiveness of apalutamide in Japanese men with mCSPC, despite a substantial portion requiring dose reduction within a year among the initial full dose recipients.

Characterizing the real-world economic burden of metastatic castration-sensitive prostate cancer in the United States

AIMS

To describe healthcare resource utilization (HRU) and costs of patients with metastatic castration-sensitive prostate cancer (mCSPC).

METHODS

Linked data from Flatiron Metastatic PC Core Registry and Komodo's Healthcare Map were evaluated (01/2016-12/2021). Patients with chart-confirmed diagnoses for metastatic PC without confirmed castration resistance in Flatiron who initiated androgen deprivation therapy (ADT) monotherapy or advanced therapy for mCSPC in 2017 or later (index date) with a corresponding pharmacy or medical claim in Komodo Health were included. Advanced therapies considered were androgen-receptor signaling inhibitors, chemotherapies, estrogens, immunotherapies, poly ADP-ribose polymerase inhibitors, and radiopharmaceuticals. Patients with <12 months of continuous insurance eligibility before index were excluded. Per-patient-per-month (PPPM) all-cause and PC-related HRU and costs (medical and pharmacy; from a payer's perspective in 2022 $USD) were described in the 12-month baseline period and follow-up period (from the index date to castration resistance, end of continuous insurance eligibility, end of data availability, or death).

RESULTS

Of 871 patients included (mean age: 70.6 years), 52% initiated ADT monotherapy as their index treatment without documented advanced therapy use. During baseline, 31% of patients had a PC-related inpatient admission and 94% had a PC-related outpatient visit; mean all-cause costs were $2551 PPPM and PC-related costs were $839 PPPM with $787 PPPM attributable to medical costs. Patients had a mean follow-up of 15 months, during which 38% had a PC-related inpatient admission and 98% had a PC-related outpatient visit; mean all-cause costs were $5950 PPPM with PC-related total costs of $4363 PPPM, including medical costs of $2012 PPPM.

LIMITATIONS

All analyses were descriptive; statistical testing was not performed. Treatment effectiveness and clinical outcomes were not assessed.

CONCLUSION

This real-world study demonstrated a significant economic burden in mCSPC patients, and a propensity to use ADT monotherapy in clinical practice despite the availability and guideline recommendations of advanced life-prolonging therapies.

Advances in the treatment of metastatic prostate cancer

The field of metastatic prostate cancer (mPCa) has seen unprecedented therapeutic advances in the past decade. In the past 2 years, recent approvals include the triplet therapy regimens of androgen deprivation therapy (ADT), docetaxel, and an androgen receptor (AR) pathway inhibitor (ARPI) in the castration-sensitive setting and lutetium-177 vipivotide tetraxetan (177Lu-PSMA-617) and the combination of poly(ADP) ribose polymerase (PARP) inhibitors (PARPis) and ARPIs in the castration-resistant setting. With many agents currently undergoing investigation in registration trials, the therapeutic armamentarium will expand rapidly, making treatment selection and sequencing challenging. Herein, we review the landmark clinical trials ongoing or reported in the past 2 years, discuss the optimal approach to treatment selection, and provide insight into future directions.

Transcriptomic and clinical heterogeneity of metastatic disease timing within metastatic castration-sensitive prostate cancer

BACKGROUND

Metastatic castration-sensitive prostate cancer (mCSPC) is commonly classified into high- and low-volume subgroups which have demonstrated differential biology, prognosis, and response to therapy. Timing of metastasis has similarly demonstrated differences in clinical outcomes; however, less is known about any underlying biologic differences between these disease states. Herein, we aim to compare transcriptomic differences between synchronous and metachronous mCSPC and identify any differential responses to therapy.

PATIENTS AND METHODS

We performed an international multi-institutional retrospective review of men with mCSPC who completed RNA expression profiling evaluation of their primary tumor. Patients were stratified according to disease timing (synchronous versus metachronous). The primary endpoint was to identify differences in transcriptomic profiles between disease timing. The median transcriptomic scores between groups were compared with the Mann-Whitney U test. Secondary analyses included determining clinical and transcriptomic variables associated with overall survival (OS) from the time of metastasis. Survival analysis was carried out with the Kaplan-Meier method and multivariable Cox regression.

RESULTS

A total of 252 patients were included with a median follow-up of 39.6 months. Patients with synchronous disease experienced worse 5-year OS (39% versus 79%; P < 0.01) and demonstrated lower median androgen receptor (AR) activity (11.78 versus 12.64; P < 0.01) and hallmark androgen response (HAR; 3.15 versus 3.32; P < 0.01). Multivariable Cox regression identified only high-volume disease [hazard ratio (HR) = 4.97, 95% confidence interval (CI) 2.71-9.10; P < 0.01] and HAR score (HR = 0.51, 95% CI 0.28-0.88; P = 0.02) significantly associated with OS. Finally, patients with synchronous (HR = 0.47, 95% CI 0.30-0.72; P < 0.01) but not metachronous (HR = 1.37, 95% CI 0.50-3.92; P = 0.56) disease were found to have better OS with AR and non-AR combination therapy as compared with monotherapy (P value for interaction = 0.05).

CONCLUSIONS

We have demonstrated a potential biologic difference between metastatic timing of mCSPC. Specifically, for patients with low-volume disease, those with metachronous low-volume disease have a more hormone-dependent transcriptional profile and exhibit a better prognosis than synchronous low-volume disease.

Early prostate-specific antigen response among Black and non-Black patients with advanced prostate cancer treated with apalutamide

Aim: To assess reduction in prostate-specific antigen (PSA) levels among Black and non-Black patients treated with apalutamide for non-metastatic castration-resistant prostate cancer (nmCRPC) or metastatic castration-sensitive prostate cancer (mCSPC). Patients & methods: Patients were identified from electronic medical data. PSA reduction (≥50%, ≥90% or below 0.2 ng/ml) after apalutamide initiation was assessed. Results: A total of 313 patients with nmCRPC and 260 patients with mCSPC were identified. The majority of patients treated with apalutamide achieved a 90% reduction in PSA regardless of indication or race. The proportion of patients achieving a PSA reduction at any level was similar among Black and non-Black patients and was consistent with apalutamide phase III trials. Conclusion: In routine clinical practice, apalutamide consistently produced reduction in PSA levels in Black and non-Black men with nmCRPC or mCSPC.

Safety and efficacy of apalutamide in Japanese patients with metastatic castration-sensitive prostate cancer receiving androgen deprivation therapy: Final report for the Japanese subpopulation analysis of the randomized, placebo-controlled, phase III TITAN study

Objectives

The TITAN study is a randomized, double‐blind, placebo‐controlled, multinational trial that evaluated apalutamide with androgen deprivation therapy in patients with metastatic castration‐sensitive prostate cancer. At the first interim analysis in the Japanese subpopulation (median follow‐up 25.7 months), there was an improvement in overall survival and radiological progression‐free survival with apalutamide versus placebo. Here, we report the final analysis results for the Japanese subpopulation.

Methods

Patients were randomized 1:1 to receive apalutamide 240 mg or placebo. After the first interim analysis, protocol treatment was unblinded, and crossover was allowed. Efficacy and safety were evaluated in the preplanned, event‐driven final analysis.

Results

Fifty‐one patients were Japanese (apalutamide n = 28; placebo n = 23). After a median follow‐up of 46.0 months, the median overall survival was not reached neither in the apalutamide nor the placebo group; the hazard ratio was 0.45, favoring apalutamide, which was consistent with the overall population. Hazard ratios for time to cytotoxic chemotherapy (0.39), time to pain progression (0.87), and time to chronic opioid use (0.82) also favored apalutamide and were comparable with those of the overall population. Time to prostate‐specific antigen progression and progression‐free survival 2, respectively, was favored in the apalutamide group (0.21 and 0.44). Apalutamide was associated with higher incidences of rash and fracture in the Japanese subpopulation compared with the overall population.

Conclusions

The efficacy of apalutamide with androgen deprivation therapy in Japanese patients was consistent with efficacy demonstrated in the overall population. No new safety concerns emerged with long‐term follow‐up.

Cost-effectiveness of enzalutamide versus apalutamide versus androgen deprivation therapy alone for the treatment of metastatic castration-sensitive prostate cancer in Canada

AIMS

There are no direct comparisons of the relative cost-effectiveness of second-generation anti-androgens (enzalutamide and apalutamide) used in managing metastatic castration-sensitive prostate cancer (mCSPC) in Canada. This study compared the cost-effectiveness of enzalutamide versus apalutamide versus androgen deprivation therapy (ADT) alone (standard of care) in patients with mCSPC from the Canadian public payer perspective using a Markov model with a 15-year time horizon.

MATERIALS AND METHODS

Efficacy data for enzalutamide and ADT alone were informed by the ARCHES and ENZAMET clinical trials, while a Bayesian network meta-analysis enabled comparison with apalutamide and ADT alone.

RESULTS

Over the 15-year period, enzalutamide achieved the highest number of life-years (LY, 7.6) and quality-adjusted life-years (QALY, 5.62) compared with apalutamide (LY, 6.1; QALY, 4.59) and ADTs (LY, 4.9; QALY, 3.61). Enzalutamide incurred the most costs ($349,345) compared with apalutamide ($294,349) and ADT ($162,550). Sequential analysis showed that enzalutamide lies on the cost-effectiveness frontier with ADT alone (incremental cost-effectiveness ratio: $92,868/QALY), with apalutamide extendedly dominated through enzalutamide and ADT alone.

LIMITATIONS

Limitations include the heterogeneity of the studies included in the network meta-analysis and the validations for the treatment sequencing assumptions in the modeling.

CONCLUSIONS

Enzalutamide was the most effective treatment option for mCSPC in the Canadian market, with the greatest LYs and QALYs, and incurred the most costs.

The Role of Fast and Deep PSA Response in Castration-sensitive Prostate Cancer

BACKGROUND

Outcomes of castration-sensitive prostate cancer (CSPC) have improved owing to new therapies and early treatment, previously reserved for castration-resistant disease (CRPC). Prostatic-specific antigen (PSA) remains the most used marker to follow-up patients under treatment, but only limited data are available about the prognostic role of its changes over time and the impact of response to subsequent therapies. This analysis aims to assess the prognostic role of the magnitude and velocity of PSA response in CSPC and describe how this may affect the outcome to subsequent treatment outcomes in CRPC.

PATIENTS AND METHODS

A retrospective analysis was performed on patients with de novo CSPC referring to six oncology centers in Italy. Clinical and pathological features were recorded. PSA response (PSA50), defined as a decrease > 50% compared to baseline, PSA velocity (PSAv), defined as any decrease in PSA levels over time and the deep and fast PSA response (4mPSA50), defined as the PSA response reached within the threshold of 4 months from the beginning of androgen deprivation therapy (ADT) have been evaluated for their impact on survival. Survivals were estimated using the Kaplan-Meier method and compared across groups using the log-rank test. Cox proportional-hazard models, stratified according to baseline characteristics, were used to estimate hazard ratios for overall survival (OS).

RESULTS

A totals of 94.4% of patients had PSA50, which was correlated to longer OS compared to patients without PSA50 (56.0 vs. 14.8 months; p<0.001). The median PSAv was 6.9 (ng/dl)/month, which was predictive for longer OS: Each decrease of 1 (ng/dl)/month was able to improve OS by 0.2% (HR=0.998, 95%CI=0.997-1.000; p=0.008). A total of 47.9% of patients reached 4mPSA50, with a median OS and progression-free survival (PFS) to ADT-based therapy of 101.0 and 23.4 months compared to 41.9 and 11.0 months for those who did not (p<0.001), respectively. The independent prognostic role of 4mPSA50 was retained even when evaluated in multivariable analysis adjusted for other baseline characteristics and early docetaxel for CSPC. In CRPC, 4mPSA50 evaluated during CSPC retains its prognostic role even if it does not predict a different outcome between patients treated with abiraterone/enzalutamide or taxanes.

CONCLUSION

Achieving a deep and fast PSA response correlates with a better outcome in patients with de novo mCSPC, also positively influencing the prognosis of the subsequent first-line therapy for CRPC disease.

Abiraterone acetate in combination with prednisone in the treatment of prostate cancer: safety and efficacy

INTRODUCTION

Metastatic prostate cancer is a life-threatening disease and an important public health concern with prevalence rates varying drastically between high- and low-income countries. Androgen-deprivation therapy alone has been the first-line treatment option for decades, temporarily controlling disease until invariable tumor regression. At the castration-resistant stage, metastatic disease becomes lethal. In recent years several new treatments, including second-generation hormone therapies, have proven to be life-prolonging in metastatic castration-resistant prostate cancer, and at an earlier hormone-sensitive stage. Abiraterone acetate in combination with prednisone was the first approved hormone therapy demonstrating survival benefit, and represents, to date, an alternative, or a second-line treatment after taxane-based chemotherapy, in addition to androgen-deprivation therapy, in hormone sensitive, and metastatic castration-resistant prostate cancer.

AREA COVERED

We performed a literature review of papers from 2012 to 2020 using PubMed, Web of Science, and Embase searching for the safety and efficacy of abiraterone acetate in prostate cancer management. Search results were limited to phase III-IV trials and post hoc analysis of Phase III trials evaluated Abiraterone acetate in the English language.

EXPERT OPINION

This literature review confirms the role of abiraterone acetate in the therapeutic landscape with well-proven safety and efficacy, demonstrated in trials and post-approval studies.